The document discusses the components and functioning of fuel systems in engines. It describes two main types of fuel systems: petrol and diesel. The petrol system uses a carburetor to mix air and fuel before combustion, while the diesel system injects fuel directly into compressed air in the cylinder. The key components of both systems include a fuel tank, air supply system, fuel filters, fuel pump, and injectors or carburetor for regulating the air-fuel ratio. Proper functioning of the fuel system is important to efficiently deliver the correct fuel-air mixture for combustion.
2. 2
1.Fuel System
➢ The fuel delivery system to the engine
➢ 2 systems
1. Petrol system
✓ Petrol and air are first mixed in definite
proportions (usually 1:15) by a device called
Carburetor
✓ Then mixture is fed into the cylinder
✓ Finally the mixture is burnt by an electric spark
generated at the end of the compression
3. • Fuel Tank
• Fuel Line
• Fuel Filter
• Air Cleaner
• Fuel Injection Pump
• Fuel Injector
• Pressure Regulator
3
Fuel Supply Components
5. 5
1.Fuel System…
2. Diesel system
✓ Only air is drawn into the cylinder
✓ Air is compressed during the compression
stroke
✓ At the end of the compression stroke diesel
fuel is sprayed under a pressure into the
cylinder
✓ Sprayed fuel is burnt by the heat of
compressed air
7. 7
Components of the fuel system
1. Fuel tank (storage)
➢ Regardless the fuel type
it is necessary to have a
tank to store
2. Air supply system
➢ A device to supply clean
air is needed to provide
O2 for burning the fuel
➢ There is a device called
Air Cleaner
8. 8
Components of the fuel system…
3. Device to regulate
air:fuel ratio
➢ In petrol engines - there
is a device called
carburetor
➢ In Diesel engines – Air
fuel mixing occurs in the
cylinder
➢ Diesel fuel is injected
into the cylinder at the
end of the compression
stroke by a device called
injector
9. 9
Components of the fuel system…
4. Fuel filters
➢ Filters are used to clean the
fuel to ensure that fuel does
not clog in either the
carburetor or fuel injector
➢ Therefore filters are used at
several points in the supply
line
I. Screen at fuel tank filter
II. Sediment blow
III. A number of fuel filters on
supply line
IV. Fuel filter at the entrance to
the injector pump
10. 10
Components of the fuel system…
5. Fuel pump
➢ Fuel tank may be
located above or
below the carburetor
✓ Above – fuel flow due
to gravity
✓ Below – A device is
needed to lift fuel
“called as FUEL
PUMP”
11. 11
Components of the fuel system…
6. Fuel injector
✓ Used in diesel engines
✓ Inject fuel at a very
high pressure into the
cylinder
7. Manifold
➢ Collection of tabular
components used to
conduct air or the air
fuel mixture into the
engine
12. 12
Air cleaners
➢ A vital component of the
fuel system
➢ As the air is finally used
in the cylinder, it very
important that is
completely free from dirt
and dust
➢ If not –
✓ Clogging vital passage
and components
✓ Can foam a grinding
paste which will ruin the
cylinder
13. 13
Air cleaners…
❖ Types of air cleaners – 2
types
1. Dry air cleaners
2. Oil bath air cleaners (wet)
I. Dry air cleaners
➢ Makes using disposal
material like felt or waxed
paper
➢ The filter traps all incoming
dirt in its folds and allows
clean air to pass to the
engine
➢ The disposal element
should always replace at
the stated service interval
14. 14
Air cleaners…
II. Wet type
➢ Air is drawn and passed
over a trough of oil
➢ Dusts get deposited in the
oil
➢ Air escape to the engine
through a wire mesh (trap
any dirt that may have
escaped in the oil bath)
➢ Heavier items such as
straw, leaves are trapped
by a pre-cleaner located at
the entrance of the air
cleaner
15. 15
Components of the fuel system…
➢ Major components
of petrol fuel system
1. Fuel tank
2. Fuel pump
3. Carburetor
➢ Major components
of diesel fuel system
1. Fuel tank
2. Filters
3. Fuel injection pump
4. Fuel injectors
